In the following discussion certain articles and methods will be described for background and introductory purposes. Nothing contained herein is to be construed as an “admission” of prior art. Applicant expressly reserves the right to demonstrate, where appropriate, that the articles and methods referenced herein do not constitute prior art under the applicable statutory provisions.
Bacteremia and fungemia are life-threatening infections that require timely administration of appropriate antimicrobial therapy to prevent significant mortality. The term “septicemia” is used to describe the presence of organisms within the blood in association with laboratory and/or clinical findings that are indicative of infection such as fever, chills, malaise, tachycardia, hyperventilation, shock and leucocytosis. Weinstein et al. (Rev. Infect. Dis. 5: 54-70 (1983)) determined that the overall rate of mortality was 42% among 500 episodes of bacteremia and fungemia, with approximately half of the deaths attributable directly to septicemia. It has long been recognized, however, that the majority of bacteremias and fungemias are associated with the recovery of very low numbers of organisms from the blood. Indeed, it is not uncommon for less than 1 organism/mL of blood to be present, particularly after the initiation of antimicrobial therapy. The severity of such infections and the diverse spectrum of potential pathogens, therefore, necessitate highly sensitive methods of diagnosis that are capable of identifying a broad spectrum of bacteria and fungi. Classically, diagnosis is achieved through the use of broad-based culture methods that are amenable to the growth of a wide variety of pathogens from low-level inocula. Following growth and isolation in pure culture, the organisms are identified through the application of a battery of biochemical tests. Antimicrobial susceptibility testing is then conducted to permit modification of empirical therapy to an efficacious pathogen-specific regimen that minimizes cost and toxicity. There remains, however, a need to reduce the time between collection of specimens from a patient and administration of targeted antimicrobial therapy to provide an opportunity to reduce morbidity and mortality, defray the cost of therapy and hospitalization, and minimize the spread of antimicrobial drug resistance caused by ineffective or inappropriate therapy.